Long long ago in an ancient land, there lived a very wise man who happened to be the Vizier at the court of a great Sultan. 

Months and years passed by and the great Sultan died, and his young prince replaced him. Being young, the prince lacked experience. He started spending more than what his father used to. The wise Vizier decided to teach the brash prince a lesson! 

The prince set a contest and as a reward, decided to give the winner whatever he wishes, boasting of his wealth, being under the illusion that his wealth is virtually endless. The Vizier won, and asked the prince for the prize: a single grain of wheat and a chess board! 

"What?! Just a grain of wheat! Are you insulting my wealth?" yelled the prince.
"No! Your majesty!" The Vizier explained. "You have to promise to double that grain of wheat until the chess board is full, so on the first day you give me one grain of wheat on the first square of the chess board, on the second day you double it on the second square (giving me two grains), on the third, you double that on the third square (giving me four grains), and so on, until the sixty fourth square on the chess board."
"I would thought you being so smart", the young prince said. "You would ask for something more substantial. Anyway, if this is your wish I will grant you that."

 

Leave us your email, we will invite you for next LabArt!

Watch the video of the previous editions (website in Italian)

 

And so, on the second day, the Vizier got 2 grains, on the third, he got 4 grains, and the young prince couldn't help himself making fun of the Vizier. 

By the sixth day, the Vizier got 32 grains of wheat. By the eighth day and the end of the first row, he got a mere 128 grains. By the sixteenth day and the end of the second row, he got 32,768 grains. 

Where was this leading to? Was it worth it for the Vizier?

By the end of the game (it was a mind game, wasn't it?) can you guess how many grains the Vizier would get in all?

The prince could not provide enough grains to give the Vizier a chess board's worth of grains. Why? Study the progress of the number of grains on the individual squares and the corresponding running total in the table below. There are not enough grains in the whole world to give the Vizier the sum of 18,446,744,073,709,551,615 grains!  Indeed, that many grains would cover the entire earth several inches deep.

 

Square

Grains on Square

Running Total

1

1

1

2

2

3

3

4

7

4

8

15

5

16

31

6

32

63

7

64

127

8

128

255

9

256

511

10

512

1,023

11

1,024

2,047

12

2,048

4,095

13

4,096

8,191

14

8,192

16,383

15

16,384

32,767

16

32,768

65,535

17

65,536

131,071

18

131,072

262,143

19

262,144

524,287

20

524,288

1,048,575

21

1,048,576

2,097,151

22

2,087,152

4,194,303

23

2,097,152

8,388,607

24

8,388,608

16,777,215

25

16,777,216

33,554,431

26

33,554,432

67,108,863

27

67,108,864

134,217,727

28

134,217,728

268,435,455

29

268,435,456

536,870,911

30

536,870,912

1,073,741,823

31

1,073,741,824

2,147,483,647

32

2,147,483,648

4,294,967,295

33

4,294,967,296

8,589,934,591

34

8,589,934,592

17,179,869,183

35

17,179,869,184

34,359,738,367

36

34,359,738,368

68,719,476,735

37

68,719,476,736

137,438,953,471

38

137,438,953,472

274,877,906,943

39

274,877,906,944

549,755,813,887

40

549,755,813,888

1,099,511,627,775

41

1,099,511,627,776

2,199,023,255,551

42

2,199,023,255,552

4,398,046,511,103

43

4,398,046,511,104

8,796,093,022,207

44

8,796,093,022,208

17,592,186,044,415

45

17,592,186,044,416

35,184,372,088,831

46

35,184,372,088,832

70,368,744,177,663

47

70,368,744,177,664

140,737,488,355,327

48

140,737,488,355,328

281,474,976,710,655

49

281,474,976,710,656

562,949,953,421,311

50

562,949,953,421,312

1,125,899,906,842,623

51

1,125,899,906,842,624

2,251,799,813,685,247

52

2,251,799,813,685,248

4,503,599,627,370,495

53

4,503,599,627,370,496

9,007,199,254,740,991

54

9,007,199,254,740,992

18,014,398,509,481,983

55

18,014,398,509,481,984

36,028,797,018,963,967

56

36,028,797,018,963,968

72,057,594,037,927,935

57

72,057,594,037,927,936

144,115,188,075,855,871

58

144,115,188,075,855,872

288,230,376,151,711,743

59

288,230,376,151,711,744

576,460,752,303,423,487

60

576,460,752,303,423,488

1,152,921,504,606,846,975

61

1,152,921,504,606,846,976

2,305,843,009,213,693,951

62

2,305,843,009,213,693,952

4,611,686,018,427,387,903

63

4,611,686,018,427,387,904

9,223,372,036,854,775,807

64

9,223,372,036,854,775,808

18,446,744,073,709,551,615


     

 

  

 

 

 

scacchi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chess i pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chess i pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chess i pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chessi pisa, pisa scacchi, 113 via santamaria pisa, 113viasantamaria, pisa scacchi, chess pisa, pisa chess